Questions

Question 1

What is the time constant?

Answer 1

The amount of time it takes for a signal to fall to 37% of the original calibration amplitude is called the time constant.
It is also sometimes referred to as the fall time
The rise time is the time it takes a signal to rise to 63% of its peak amplitude

Question 2

Which filter would be used to adjust the rise time of a signal?

Answer 2

The HHF, or high frequency filter, is used to adjust the rise time of a signal.
The higher this filter is set the faster the signal wave will rise.
The LFF is used to adjust the time constant, or fall time.
Gain and sensitivity mean the same thing and will not affect the shape of the wave, only the size of the signal display.

Question 3

What is the difference between a thermocouple and a pressure transducer?

Answer 3

The thermocouple, also called a thermistor, measures the changes in temperature of air going into and out of the nose and mouth and thereby gives an airflow signal.
The pressure transducer creates an airflow signal by measuring the change in the air pressure going into and out of the nose only.
Neither sensor can measure the air volume

Question 4

What is the difference between SpO2 and SaO2?

Answer 4

Both SpO2 and SaO2 are measures of the same thing, the amount of hemoglobin that is saturated with oxygen in a patient’s blood, but SaO2 is the more accurate measurement because it is measured by an arterial blood gas.
If the total circumference of a head is 58 cm, using the International 10-20 Electrode

Question 5

If the total circumference of a head is 58 cm, using the International 10-20 Electrode Placement System, what is the distance between C3 and O1

Answer 5

If the total circumference of the head is 58 cm then C3 and )1 are 50% of the total circumference of the head away from each other
When dealing with percentages of the total head circumference in electrode placement, multiply the total circumference by the percentage that a lead should be place in relation to your reference lead.
In the case 58 x 50% (0.5) yields the correct answer of 29 cm

Question 6

Using the International 10-20 Electrode Placement System, the C4 is located what percentage of the total circumference away from the C3 lead?

Answer 6

The C4 lead is located on the right side of the head 40% of the total circumference of the head away from the C3 lead that is on the left side of the head.
Directly in between the two (20% of the total circumference of the head) is the Cz ground lead
And example of this would be if a head had a total circumference of 52 cm the the C3 would be 20.8 cm away from the C4 lead

Question 7

Where is the O1 lead located in relation to the T3 lead?

Answer 7

The O1 lead is on the left side of the head, 20% of the total circumference of the head behind the T3 lead.
The O2 lead is on the right side of the head, 20% of the total circumference of the head behind the T4 lead
An easy way to remember which side of the head a lead is on is to remember odd numbered leads are on the left (e.g., O1, C3, T3) and even numbered leads are on the right (e.g., O2, C4, T4)

Question 8

________ is measured in Herts (Hz) and _________ in microvolts (uV)

Answer 8

Frequency, or the number of times a wave occurs, is measured in Hz, or cycles per second.
This is the number of times a wave will repeat itself in one second.
Voltage is measured in volts, and in polysomnography, in uV.
Amplitude is a measure of the height of a wave; therefore the more microvolts, the bigger the wave

Question 9

In polysomnography, sensitivity is generally measured in?

Answer 9

Sensitivity is measured in uV/mm.
What this means is that for each microvolt of a wave, the display will measure it in one mm.
This also means that the larger the number of uV/mm, the smaller the vave will be displayed, because it will take more voltage to change the signal.